bug#19547: Patch for this bug

[Thierry Volpiatto]

I have installed Parcellite (a clipboard manager).
When it is running I can reproduce the bug at every time when running
helm-find-files on a very large directory, but with the patch applied
and 
(setq while-no-input-ignore-events '(focus-in focus-out help iconify
deiconify selection-request))

it is now working as expected, the listing of directory popup
immediately.

-- 
Thierry